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Commit 85f6f029 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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ftrace/x86: Add macro MCOUNT_REG_SIZE for amount of stack used to save mcount regs 

The macro save_mcount_regs saves regs onto the stack. But to uncouple the
amount of stack used in that macro from the users of the macro, we need
to have a define that tells all the users how much stack is used by that
macro. This way we can change the amount of stack the macro uses without
breaking its users.

Also remove some dead code that was left over from commit fdc841b5
"ftrace: x86: Remove check of obsolete variable function_trace_stop".

Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1411262304010.3961@nanos



Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 527aa75b

arch/x86/kernel/mcount_64.S

+12 −12
Original line number Diff line number Diff line
@@ -21,6 +21,9 @@ 
# define function_hook	mcount

#endif



/* Size of stack used to save mcount regs in save_mcount_regs */

#define MCOUNT_REG_SIZE		(SS+8)



/*

 * gcc -pg option adds a call to 'mcount' in most functions.

 * When -mfentry is used, the call is to 'fentry' and not 'mcount'
@@ -42,7 +45,7 @@ 
	 /*

	  * We add enough stack to save all regs.

	  */

	subq $(SS+8), %rsp

	subq $MCOUNT_REG_SIZE, %rsp

	movq %rax, RAX(%rsp)

	movq %rcx, RCX(%rsp)

	movq %rdx, RDX(%rsp)
@@ -51,7 +54,7 @@ 
	movq %r8, R8(%rsp)

	movq %r9, R9(%rsp)

	 /* Move RIP to its proper location */

	movq SS+8+\added(%rsp), %rdi

	movq MCOUNT_REG_SIZE+\added(%rsp), %rdi

	movq %rdi, RIP(%rsp)

	.endm
@@ -63,7 +66,7 @@ 
	movq RDX(%rsp), %rdx

	movq RCX(%rsp), %rcx

	movq RAX(%rsp), %rax

	addq $(SS+8), %rsp

	addq $MCOUNT_REG_SIZE, %rsp

	.endm



/* skip is set if stack has been adjusted */
@@ -79,7 +82,7 @@ GLOBAL(\trace_label) 
	subq $MCOUNT_INSN_SIZE, %rdi

	/* Load the parent_ip into the second parameter */

#ifdef CC_USING_FENTRY

	movq SS+16+\added(%rsp), %rsi

	movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi

#else

	movq 8+\added(%rbp), %rsi

#endif
@@ -172,7 +175,7 @@ ENTRY(ftrace_regs_caller) 
	movq %rbp, RBP(%rsp)

	movq %rbx, RBX(%rsp)

	/* Copy saved flags */

	movq SS+8(%rsp), %rcx

	movq MCOUNT_REG_SIZE(%rsp), %rcx

	movq %rcx, EFLAGS(%rsp)

	/* Kernel segments */

	movq $__KERNEL_DS, %rcx
@@ -180,7 +183,7 @@ ENTRY(ftrace_regs_caller) 
	movq $__KERNEL_CS, %rcx

	movq %rcx, CS(%rsp)

	/* Stack - skipping return address and flags */

	leaq SS+8*3(%rsp), %rcx

	leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx

	movq %rcx, RSP(%rsp)



	/* regs go into 4th parameter */
@@ -195,11 +198,11 @@ GLOBAL(ftrace_regs_call) 


	/* Copy flags back to SS, to restore them */

	movq EFLAGS(%rsp), %rax

	movq %rax, SS+8(%rsp)

	movq %rax, MCOUNT_REG_SIZE(%rsp)



	/* Handlers can change the RIP */

	movq RIP(%rsp), %rax

	movq %rax, SS+8*2(%rsp)

	movq %rax, MCOUNT_REG_SIZE+8(%rsp)



	/* restore the rest of pt_regs */

	movq R15(%rsp), %r15
@@ -225,9 +228,6 @@ GLOBAL(ftrace_regs_caller_end) 


	jmp ftrace_return



	popfq

	jmp  ftrace_stub



END(ftrace_regs_caller)
@@ -266,7 +266,7 @@ ENTRY(ftrace_graph_caller) 
	save_mcount_regs



#ifdef CC_USING_FENTRY

	leaq SS+16(%rsp), %rdi

	leaq MCOUNT_REG_SIZE+8(%rsp), %rdi

	movq $0, %rdx	/* No framepointers needed */

#else

	leaq 8(%rbp), %rdi